Method of making hollow valves



p 21, 1937- A. T. COLWELL 2,093,773

METHOD OF MAKING HOLLOW VALVES Filed May 16, 1951 Patented Sept. 21, 1937 METHOD OF MAKING HOLLOW VALVES Archie r. Colwcll, Cleveland, Ohio, minor to Thompson Products, Incorporated, Cleveland, Ohio, a corporation of Ohio Application May 16, 1931, Serial No. 537,829

3 Claims. (01. 29-156.?)

This invention relates to a method of makin valves and particularly to a method of making hollow valves for internal combustion engines. I

Hollow stem valves, filled with a cooling medium such as salt have of late years come into use for high compression internal combustion engines. The cost of making such valves, however. has heretofore been very high and consequently their use has been limited to expensive installations where extreme operating conditions require the best regardless of cost.

It is an object of this invention to provide a method of making hollow stem valves at a reasonable cost.

It is a further object of this invention to provide a method of making hollow stem valves which eliminates the step of drilling the valve stem.

It is a particular object of this invention to provide a method of making hollow stem, hollow headed valves which eliminates the costly operations of drilling or reaming the valve head.

These and other objects of this invention will be apparent from the following description and appended claims.

This invention (in a preferred form) is illustrated in the accompanying drawing and hereinafter more fully described.

On the drawing:

Figure 1 is a section view of a blank provided with a metallic insert for use in forming'a hollowvalve.

Figures 2 and 3 illustrate steps in forming a valve according to this invention.

Figures 4, 5 and 6 illustrate steps in forming a valve according to a modified form of this invention.

Figure 7 is a sectional view of a completed valve.

In carrying out this invention, a blank I of the shape shown in Figure l is provided. The blank I is preferably formed from a suitable valve material such as tungsten steel or chromium steel as by forging or cutting a slug from a piece of rolled stock. A recess 2 is drilled into the blank I longitudinally thereof. The recess 2 is preferably cylindrical and concentric with the blank I, extending through one end thereof and for a considerable distance within the blank.

An insert 3 is fitted in the recess 2 or the recess 2 may be filled by pouring a molten metal therein. In either case, the metal of the insert 3 should have a relatively low melting point compared to the melting point of the metal of blank i. Such metals as copper and aluminum and their alloys prove satisfactory when used with the steels set out above.

g The composite blank thus formed is heated to a forging temperature and subsequently worked to form a head 4 and stem 5 thereon. 5 This step may be accomplished by extruding the heated blank through a suitable die. Pressure is applied to one end of the blank so as to spread out the headportion and to extrude the stem portion through the die. In this operation, the 10 metallic insert 3 is drawn into the stem to form a core 6 with a portion I thereof spread out within the head.

As shown in Figures 1, 2, and 3, the blank I is worked with its recessed end downwardly so as 15 to form the stem. The core 6 extends to the end of the stem and due to its expansion during the hot working process, some of the metal of the core may be forced out of the open end of the valve stem 5 as at 8. Heat is then applied to the 20 valve, preferably directly to the metal core 6 to melt the core metal and permit it to be poured out of the valve, thus leaving the bore 9 in the stem and the recess ID in the head 5.

In the modified form of the invention shown in 25 Figures 4, 5 and 6 the recessed end of the blank I is upright, so that in the working of the blank I, pressure is applied to the recessed end to form it into the head ll while the closed end is-drawn out into the stem l2. The metal of the insert 3 30 spreads out in the forging or die pressing operation to form a core l3 and the pressure applied to the blank causes the metal thereof to partially cover the core l3 by forming a flange ll about the core filled aperture I5. Sufllcient heat 35 is thereafter applied to the insert and the metal thereof is poured out through the aperture l5 to leave a bore IS in the stemand a recess H in the head of the valve.

The aperture l5 and thelower end of the bore 40 9 are closed in any appropriate manner as by welding plugs therein, and the valve is finished by suitable forging andmachining operations.

The complete valve comprises a head I 8' and a stem IS with a bore 20 therein extendinginto 45 the head i8 and there terminating in an enlarged recess 2|.

It will thus be seen that this invention provides an expedient method of making a hollow valve without the necessity of drilling the fin- 50 ished valve and one in which the recess in the head is formed in the working of the valve blank.

Many changes may be made in the steps of the process and arrangement thereof and-I do not wish to be limited otherwise than is necessary by 55 the prior art and the scope of the appended claims.

I claim as my invention:

1. The method of making hollow valves which comprises providing a metal blank having a blind bore extending longitudinally from one end thereof into close proximity to the other end, filling the bore of the blank with a-metal having a melting point substantially below the melting point of the blank metal, working the composite blank thus formed to form a valve head on one end thereof with the insert metal spreadout into the head and a valve stem on the other 'end thereof integrally united with the head, said working operation forcing some 01 the' insert metal out of the opening of the bore to maintain the bore open during the working operation, heating the valve thus formed above the melting point of the insert metal, removing the molten metal and plugging the opening to the cavity in the valve.

2. The method 01' making hollow valves which comprises providing a recessed metal blank with the recess extending from one end of the blank into close proximity to the other end, filling the stantially below the melting point of the blank metal, forging the composite metal blank thus formed to provide an enlarged head thereon and an elongated stem with the insert metal spread out into the head and down the stem, said forging operation effecting the extrusion oi some of the insert metaltrom the recess to maintain the mouth 01' the recess open, removing the insert metal through said opening to provide a valve having an enlarged cavity in the head and a communicating cavity extending down the stem and subsequently welding a plug into the opening for sealing the cavities in the valve.

3. The method of making a hollow valve which comprises introducing a metal filler material into the recess of a recessed metal blank, simultaneously upsetting one end of the blank and drawing the opposite end of the blank to form the blank into a valve having a head and stem, said upsetting operation causing the insert metal to spread out into the head and be partially extruded from the recess, removing the insert metal from the valve to leave the valve having a continuous cavity in the head and stem thereof and plugging the opening to said cavity.

, ARCHIE T. COLWEIL. 

